In PWM control for an alternating-current motor of an EV or an HV, a current command value generated on the basis of a motor control logic such as vector control which is mounted in a control circuit is given to a PWM circuit, to thereby generate a PWM pulse for applying an output voltage having any amplitude and phase from an inverter to an alternating-current motor. Control of a torque which is generated by the interaction of a motor current with a magnetic flux which is interlinked with a winding of the alternating-current motor is required for controlling the rotational speed of an alternating-current motor and the position of a rotor at high speed. For this reason, the control circuit generates a current command value to a drive command for each phase while referring to current information which is fed back from a feedback loop of the motor current or position information of the rotor, and gives the generated value to the PWM circuit. Such general PWM control for the alternating-current motor is disclosed in, for example, PTL 1.
In the PWM control for the alternating-current motor, the rotation speed of the alternating-current motor is sufficiently slow in a carrier period of the PWM circuit. Thus, in case that a motor current acquisition period corresponding to the carrier period is generated in the acquisition of the motor current from the feedback loop, it is possible to acquire a sinusoidal motor current, and to reflect arithmetic results based on the fed-back motor current or the like in the PWM pulse. For example, in case that a sinusoidal wave is represented by more than twelve divisions with respect to a carrier period having a frequency of 10 kHz, the rotation speed of the alternating-current motor can attain up to 833 Hz.